This application claims the priority of German Patent Application Nos. 197 41 371.4 and 198 28 255.9, filed Sep. 19, 1997 and Jun. 25, 1998, respectively, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a vehicle seat with a seat cushion, adjustably fixed to the floor of a vehicle, and a backrest, which can be adjusted with respect to the seat cushion, as well as with a restraining device for the seat user.
In the case of a known vehicle seat of this type, for example from German Patent document DE 37 41 831 C2, a belt guide for the three-point safety belt, in which the shoulder belt can be suspended when the safety belt is pulled out and buckled into the belt buckle, is disposed on the side of the seat facing the side wall of the vehicle at the upper edge of the backrest. An additional belt is fastened with one of its ends at the shoulder belt in that section of the belt webbing between the first belt fixing point disposed at the side wall of the vehicle and the belt guide on the backrest and supplied at its other end with a buckle tab. The tab can be inserted into the second belt buckle, which is fastened on the side of the seat averted from the side wall of the vehicle to the side surface of the backrest. With this, the restraining device forms a four-point safety belt in the resting position with the second belt buckle as the fourth fastening point.
In the resting position of the seat user, this known four-point safety belt reliably prevents, in the case of a crash, a dynamic raising of the upper part of the body of the belted seat user; however, it cannot effectively prevent a so-called submarining, during which the seat user slides under the belt around the hip or the pelvis. Moreover, the additional belt, which hangs down loosely at the side wall of the vehicle from the shoulder belt when the seat user is in the seated position and must be fastened in some manner with its buckle tab to the side wall of the vehicle, in order to avoid rattling noises, is bothersome.
In the case of a vehicle seat, which is also known, for example from Japanese patent document JP 6-255 445 A and its abstract, the restraining device for the seat user has a three-point safety belt and an additional belt, which extends counter to the chest or shoulder belt of the three-point safety belt from the upper edge of the backrest, over the chest of the seat user, to the second belt buckle. Both belts are intended to be used in the normal seated position of the seat user, that is, with the backrest in an upright position or in a position slightly inclined to the rear. In addition to being fastened above the upper edge of the backrest at the side wall of the vehicle, the three-point safety belt is passed through a reversing fitting at the upper edge of the backrest, as a result of which the backrest cannot be swiveled completely into the resting position when the seat user is buckled up.
It is an object of the invention to optimally support the user of the above-mentioned type of vehicle seat in the resting position, even against the so-called submarining effect, without thereby causing negative repercussions on the design and use of the three-point safety belt in the seated position.
Pursuant to the invention, this and other objects are achieved by providing a vehicle seat with a seat cushion, adjustably fixed to the floor of a vehicle, and a backrest, which can be adjusted with respect to the seat cushion, as well as with a restraining device for the seat user. The restraining device has a three-point safety belt with a chest or shoulder belt extending in the seated position of the seat user over the chest of the latter, from a first belt fixing point, which is disposed above the upper edge of the backrest at a side wall of the vehicle, to a detachable belt buckle forming a second belt fixing point and fastened in the floor area on the side of the seat opposite the wall of the vehicle and with a hip or pelvis belt extending over the pelvis of the seat user from the belt buckle to a third belt fixing point, which is disposed in the floor area on the side of the seat facing the side wall of the vehicle. An additional belt, which can be utilized in a swiveled position of the backrest that is intended as a resting position for the seat user can be tightened over the chest of the seat user to a second belt buckle. In the resting position of the seat user, on the one hand, a fixed adjustment of the seat cushion and of the backrest is provided, so that the backrest can be swiveled through an obtuse angle relative to the seat cushion and the seat cushion is shifted into a front, predetermined position and inclined towards the rear and, on the other, the additional belt extends as a transverse shoulder belt from the upper edge of the backrest to the second belt buckle, which is disposed close to the floor.
The vehicle seat according to the present invention has the advantage that, by the fixed, defined adjustment of the seat cushion and the backrest in the resting position and the therewith associated downward slope of the seat cushion rearward, which can be brought about by raising the front edge of the seat cushion and/or lowering the rear edge of the seat cushion, a submarining of the user is reliably prevented, since the seat user, fastened to the seat cushion by the tightened belt around the pelvis, is supported with the buttocks in the driving direction at the adjusted seat cushion. In the event of a crash, the tendency of the upper part of the body of the seat user to be raised up, which is initiated by this fastening of the pelvis, is counteracted by the additional belt, which passes the forces into the frame of the backrest. The frame of the backrest, which advantageously is reinforced, acts here like a force limiter, which dissipates energy, in the further course, energy also being consumed in the seat frame or seat underframe of the seat cushion consisting of the seat frame and seat pad. Consequently, the raising of the passenger takes place relatively slowly overall, so that the seat user reaches the shoulder belt of the three-point safety belt with a relatively low residual velocity and residual energy. Upon reaching the shoulder belt, the effect of the three-point safety belt and, optionally, that of the passenger air bag, set in, and the seat user behaves approximately like a seat user who is in the normal, seated position before the crash. Accordingly, the stress values on the seat user are slight even in the resting position. The additional belt can also be additionally equipped with conventional safety technology, such as a belt tightener, in order to prevent slackness in the belt when the additional belt and the force limiter are put on.
In the case of the inventive vehicle seat, the three-point safety belt remains unchanged and retains its normal configuration and use function. If the additional belt, pursuant to a preferred embodiment of the invention, is fastened to the upper edge of the backrest by means of a belt retractor, the additional belt in the seated position is always in the retracted state and does not interfere in any way with the handling of the three-point safety belt when the latter is put on, or with the aesthetics of the buckled-up safety belt in the seated position or with the aesthetics of the vehicle seat in the retracted position of the three-point safety belt.
Advantageous embodiments of the inventive vehicle seat with appropriate further developments and refinements of the invention are described herein.
Pursuant to a preferred embodiment of the invention, the additional belt and the three-point safety belt are coupled together automatically in such a manner, that the additional belt cannot be pulled out of the belt retractor, as long as the belt lock of the three-point safety belt is not closed. This prevents the additional belt, properly intended for the resting position, from being put on in the seated position and ensures that the three-point safety belt is also put on in the resting position.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.